In the art of weight training, curling exercises to develop the human biceps are performed by grasping a weighted bar with one or two hands and curling the forearm upwards and back toward the upper arms.
Biceps development can be further increased by supinating the hands while curling. Supination consists of starting with a palms down position at the beginning of the curling exercise and rotating the hands to a palms up position while performing the curling exercise. Weight trainers currently use dumbells for supination type curling exercises since they allow multi-axes hand movement so the weight trainer may select hand and wrist motions which maximize muscle growth. Dumbells are slow to use and they throw the weight trainer off balance compared to a two handed curling bar. A two handed curling bar allows the weight trainer to lift heavier weights without encountering balancing problems.
Various types of weightlifting apparatus have been proposed to allow two handed curling exercises with supination. The Bailey et al weightlifting apparatus, disclosed in U.S. Pat. No. 3,384,370 utilizes a pair of rotatably mounted handles in spaced apart rings. The rings are fastened together by a straight rod. On the outside extremity of each ring is fastened a straight rod for placement of weights. The Bailey weightlifting apparatus allows single axis wrist rotation during curling exercises.
The Cole weightlifting apparatus, U.S. Pat. No. 4,461,473 provides the same function as the Bailey weightlifting apparatus but its improvements include a novel frame, a spring interconnecting the handles which supplies a biasing force that resists rotation of the handles and a method to synchronize the rotation between the two handles.
Both the Cole and Bailey weight lifting apparatus have shortcomings which have slowed their acceptance by weight trainers. They both allow rotation of wrists and hands only about one axis. The weight trainer, when curling, must bend his wrists during wrist rotation about a single axis. This causes wrist strain. Since both weightlifting apparatus allow constrained wrist rotation about a single axis, they do not provide hand motion similar to that obtained by using dumbells which allow the weight trainer to select movements that maximize muscle growth.
Both the Cole and Bailey weightlifting apparatus use multiple sets of roller bearings to support the handles and provide a means for handle rotation. The roller bearing systems are not designed for thrust loads and thus higher friction is imparted to handle rotation when thrust loads are developed while curling.
The roller bearings ride on exposed bearing surfaces which are constantly subject to contamination by foreign particulate matter. As the bearing surfaces become contaminated, a discontinuous, jerky rotational motion is imparted to the handles as the cam bearings ride over the particulate matter.
The Cole and Bailey weightlifting apparatus also lack a means for adjusting the distance between the two rotatable handle members to compensate for the varied grip lengths used by weight trainers.
It is therefore a primary object of the invention to provide a weightlifting apparatus which overcomes each of the deficiencies discussed above.
A further object of the invention is to present a weightlifting apparatus which provides a means for multiple axis wrist and hand rotation to reduce wrist strain and allow multi-axes two handed curling motion similar to that obtained when using dumbells so each weight trainer can choose wrist and hand movements which maximize muscle growth.
Another object of the invention is to provide a weightlifting apparatus with an enclosed and preloaded antifriction bearing system for smooth, continuous wrist rotation, that mounts to the weightlifting apparatus frame at a single location.
A further object of the invention is to provide a weightlifting apparatus with a means to adjust the distance between the two handles to accommodate the needs of each individual user.